The present invention is directed to a fastening element assembly and to a method of setting fastening elements, such as bolts and nails in a hard receiving material, such as concrete, stone and the like. Initially, a blind borehole is formed in the receiving material and the fastening element is driven through the base of the borehole into the receiving material. The fastening element is driven by a setting device using highpressure gases.
To set fastening elements in a receiving material, such as concrete, stone and the like, it has been known from U.S. Pat. No. 4,287,656 to drive the fastening elements into the receiving material through the base of a blind borehole previously formed in the receiving material. The fastening element is driven by high- pressure gases developed by the ignition of a explosive powder propelling charge. In this method, known per se, spalling at the surface of the receiving material is prevented and the fastening element can be placed accurately at the desired location.
This method has the disadvantage, however, that the portion of the fastening element projecting through the blind borehole does not contribute to the anchoring value. Accordingly, in comparison to the length of the fastening element extending into the receiving material, only relatively small anchoring values can be obtained. Moreover, with radial play between the fastening element and the bore of the blind borehole, externally introduced transverse forces in the region of the blind borehole of the receiving material are not absorbed or are only partially absorbed. Such a situation can lead to unfavorable loading of the anchored fastening element.